fabrication-operation-flow-visualization-surface-acoustic-wave-driven

Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we ...

Istituto Italiano di Tecnologia

Scuola Normale Superiore and Istituto Nanoscienze-CNR

High-frequency surface acoustic waves can be generated by ultrafast laser excitation of nanoscale patterned surfaces. Here we study this phenomenon in the hypersonic frequency limit. By modeling the thermomechanics from first-principles, we calculate the system's initial heat-driven impulsive response and follow its time evolution. A scheme is introduced to quantitatively access frequencies and lifetimes of the composite system's excited eigenmodes. A spectral decomposition of the calculated response on the eigemodes of the system reveals asymmetric resonances that result from the coupling between surface and bulk acoustic modes. This finding allows evaluation of impulsively excited pseudosurface acoustic wave frequencies and lifetimes and expands our understanding of the scattering of surface waves in mesoscale metamaterials. The model is successfully benchmarked against time-resolved optical diffraction measurements performed on one-dimensional and two-dimensional surface phononic crystals, probed using light at extreme ultraviolet and near-infrared wavelengths.

Probing thermomechanics at the nanoscale: impulsively excited pseudosurface acoustic waves in hypersonic phononic crystals.

By exploiting the resonant coupling between a travelling wave and the stationary modes of a cavity, we present the first scheme for integrated automatic interaction-free surface acoustic wave routing of fluids. Our scheme opens the way to the implementation of logic gates based on instantaneous liquid distribution.

Interaction-free, automatic, on-chip fluid routing by surface acoustic waves.

Spatiotemporal image correlation spectroscopy (STICS) is a simple and powerful technique, well established as a tool to probe protein dynamics in cells. Recently, its potential as a tool to map velocity fields in lab-on-a-chip systems was discussed. However, the lack of studies on its performance has prevented its use for microfluidics applications. Here, we systematically and quantitatively explore STICS microvelocimetry in microfluidic devices. We exploit a simple experimental setup, based on a standard bright-field inverted microscope (no fluorescence required) and a high-fps camera, and apply STICS to map liquid flow in polydimethylsiloxane (PDMS) microchannels. Our data demonstrates optimal 2D velocimetry up to 10 mm/s flow and spatial resolution down to 5 Î¼m.

Article	Year
Probing thermomechanics at the nanoscale: impulsively excited pseudosurface acoustic waves in hypersonic phononic crystals. Nano letters\| PubMed ID: 21910426	2011
Interaction-free, automatic, on-chip fluid routing by surface acoustic waves. Lab on a chip\| PubMed ID: 22706666	2012
Easy Monitoring of Velocity Fields in Microfluidic Devices Using Spatiotemporal Image Correlation Spectroscopy. Analytical chemistry\| PubMed ID: 23919917	2013

Marco Travagliati

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